Nondestructive testing probes are used for measuring thickness, or inspecting for flaws in critical portions of various objects, such as pipes, bridges, aircraft, castings, and turbine blades. Access to a portion of an object to be inspected may be limited by the shape of the object, or by its location relative to other objects.
Handles and wands for proper positioning of sensors on an inspection surface are known in existing practice. For instance, insertion wands for boiler tube wall inspection are known to incorporate a sensor that is attached to a semi flexible, thermoplastic tube capable of concentrically following the inside diameter of the tube. A semi flexible, plastic tube wand may not be well suited for positioning a sensor on an inspection surface that is not in a tubular test object. In non-tubular test objects, the inner surface of the object may not guide the probe to the surface, and the shape of the wand may not conform to the surface.
Other examples of probe positioning devices are straight or bent angle extension wands with a fixed angle between a sensor and a wand end. The arms of such wands are typically straight, or bent rigid tubes or rods. Still other probe positioning devices are straight or bent angle wands with a pivot yoke holding a sensor at the distal end, allowing angular movement of the sensor around the pivot axis. Straight wands are useful where it is possible to have line of sight access to the inspection surface of a test object. Straight wands are not suitable for inspecting test objects with inspection surfaces behind a bend in the object, or behind another immovable object. Bent angle wands have one or more bends at fixed distances from the handle, allowing the sensor to be placed on an inspection surface behind a bend in a test object or behind an immovable object. The angles and positions of a bent wand are designed to accommodate bends of known angles at known distances from the inspection access position, to the inspection surface on the test object. A wand designed for inspection of surfaces at certain angles and distance from an access position may not be suitable for inspecting another surface at other angles or distances. In instances such as a test surface around a bend at the end of a long straight crevice, neither a bent or straight wand will enable inspection. Where bent or straight wands are suitable, several different wands may be needed to inspect surfaces in different locations of one or more test objects. Additional wands are costly and may result in additional expenses for transportation, training, and sensor calibration.
US Pat. No. 2013/0310650 discloses a laryngoscope with a thumb-operable guided tube and an adjustable curving mechanism, which can be inserted into and released from the airway of a patient. Although this mechanism is not in the spirit of non-destructive inspection, it does place an articulating probe in a confined and obstructed space for the purpose for inspection. However the range of the obstructed space is limited to range of shape of anatomical features thereby limiting the required range and size of the device. The operation of the mechanism requires tendons retracting within rigid blades each having a fixed volume. The range of articulation is to an extent determined by the length of the tendons and blades and the dimension of the blades in the plane of articulation. The blade thickness in the plane of articulation limits the minimum thickness of the device and may prohibit inspection in confined spaces.
Available devices do not fully meet the need to accurately position sensors on a variety of obstructed surfaces of test objects, in a timely and cost effective manner. Some test objects may require equipment disassembly and reassembly to allow inspection when an appropriate wand is not available. Skilled mechanics, special tools, oil, gaskets and spare parts may be needed adding further expense and delay to an inspection. A further risk of disassembly is the possibility of incidental damage or misassembly. Furthermore, disassembly is not possible for some test objects such as cast turbine blades. It would be advantageous to inspect objects with minimal disassembly, or when inspection is not possible by other means.